GPIB as listen only device = pseudo analyzer?

[kzamora]

Ok, I get the impression from "Configuring an IEEE 488 Interface Board for Listen-Only or Talk-Only Operations Using NI-488.2" article that, if one is ingenious enough, he can make his own "SPY" program that can function to watch other GPIB devices on the IEEE bus talk...thus creating a poor man's analyzer. I realize there is GPIB+ hardware that you can buy that does this but I'm interested in leveraging my existing equipment. If this can be done, are there any cons? I.E, if you are able to watch, would you be able to discern traffice between different devices appropriately?

Maybe someone already has an app. that does this.
Thnx for any info.

[Ray K]

CON: Since you are in listen-only state you can read all the messages, but you will have no idea who the messages were sent to. So at the end of the day, you will have array of strings, but no other information.

[kzamora]

I suspected as such. However, I would think the majority of applications are between one sender and one receiver; This may be a naive statement on my part but if so, it shouldn't be difficult to discern between sender and receiver - especially, if you know the expected strings to be transmitted and received.

[GPIB_Guru]

Another potential problem is that if your system does serial polls, the response will be prepended to the subsequent data read. This is because most serial polls do not have EOI asserted. The listen-only device will receive the one byte, which is not a complete message. The next received message will be appended to the serial poll byte.

This may also not be a problemm if you are trying to spy on a very simple controller<>device application, but is one additional caveat.